giúp mk vs
3/5.x-x bằng -4/15
tớ cần rất gấp nha
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a)\(\left(4x+1\right)\left(x-3\right)-\left(x-7\right)\left(4x-1\right)=15\)
\(4x^2-11x-3-\left(4x^2-29x+7\right)=15\)
\(4x^2-11x-3-4x^2+29x-7=15\)
\(18x-10=15\)
\(x=\frac{25}{18}\)
b)\(\left(3x-5\right)\left(x+1\right)-\left(3x-1\right)\left(x+1\right)=x-4\)
\(\left(x+1\right)\left(3x-5-3x+1\right)=x-4\)
\(\left(x+1\right).\left(-4\right)-x+4=0\)
\(-4x-4-x+4=0\)
\(x=0\)
Do |x|=5;|y|=7
\(\Rightarrow x=\orbr{\begin{cases}5\\-5\end{cases};y=\orbr{\begin{cases}7\\-7\end{cases}}}\)
TH1:x=5;y=7
=>x + y = 12
x - y = -2
TH2:x=5;y=-7
=>x+y=-2
x-y=12
TH3:x=-5;y=7
=>x+y=2
x-y=-12
TH4:x=-5;y=-7
=>x+y=-12
x-y=2.
\(\left(x+1\right)+\left(x+2\right)+...+\left(x+10\right)=110\)
\(\left(x+x+...+x\right)+\left(1+2+3+...+10\right)=110\)
\(10x+55=110\)
\(10x=110-55\)
\(10x=55\)
\(x=55:10\)
\(x=5,5\)
\(10xX+\left(1+2+3+...+10\right)=110\)
\(1+2+3+...+10=\dfrac{10\left(1+10\right)}{2}=55\)
\(\Rightarrow10xX+55=110\Rightarrow10xX=55\)
\(\Rightarrow X=55:10=5,5\)
\(\frac{3}{5}x-x=\frac{-4}{15}\)
\(\Rightarrow\left(\frac{3}{5}-1\right)x=\frac{-4}{15}\)
\(\Rightarrow\frac{-2}{5}x=\frac{-4}{15}\)
\(\Rightarrow x=\frac{-4}{15}:\frac{-2}{5}=\frac{2}{3}\)
\(\text{vậy x=}\frac{2}{3}\)
\(\frac{3}{5}x-x=-\frac{4}{15}\)
\(\Leftrightarrow-\frac{2}{5}x=-\frac{4}{15}\)
\(\Leftrightarrow x=\left(\frac{-4}{15}\right):\left(-\frac{2}{5}\right)=\frac{2}{3}\)